It is well known that elemental sulfur in hydrocarbon streams, such as petroleum streams, is corrosive and damaging to metal equipment, particularly to copper and copper alloys. Sulfur and sulfur compounds may be present in varying concentrations in refined petroleum streams, such as in gasoline and distillate boiling range streams. Additional contamination will typically take place as a consequence of transporting the refined stream through pipelines that contain sulfur contaminants remaining in the pipeline from the transportation of sour hydrocarbon streams, such as petroleum crudes. The sulfur has a particularly corrosive effect on equipment, such as brass valves, gauges and in-tank fuel pump copper commutators.
The total sulfur in gasoline after 2005 will be limited to less than 30 wppm, while the total sulfur in diesel after 2006 will be limited to a maximum of 15 wppm. Elemental and organic sulfur contaminants that are picked up in the pipeline by gasoline and diesel products will adversely affect their ability to meet the ultra low sulfur specifications. Organic sulfur pick-up is any non-elemental sulfur component in the hydrocarbon stream that was not present in the hydrocarbon product stream prior to injecting it into the pipeline.
Various techniques have been reported for removing elemental sulfur from petroleum products. For example, U.S. Pat. No. 4,149,966 discloses a method for removing elemental sulfur from refined hydrocarbon fuels by adding an organo-mercaptan compound plus a copper compound capable of forming a soluble complex with the mercaptan and sulfur and contacting the fuel with an adsorbent material to remove the resulting copper complex and substantially all elemental sulfur.
U.S. Pat. No. 4,011,882 discloses a method for reducing sulfur contamination of refined hydrocarbon fluids transported in a pipeline for the transportation of sweet and sour hydrocarbon fluids by washing the pipeline with a wash solution containing a mixture of light and heavy amines, a corrosion inhibitor, a surfactant and an alkanol containing from 1 to 6 carbon atoms.
U.S. Pat. No. 5,618,408 teaches a method for reducing the amount of sulfur and other sulfur contaminants picked up by refined hydrocarbon products, such as gasoline and distillate fuels, which are pipelined in a pipeline used to transport heavier sour hydrocarbon streams. The method involves controlling the level of dissolved oxygen in the refined hydrocarbon stream that is to be pipelined.
The removal of elemental sulfur from pipelined fuels is also addressed in U.S. Pat. No. 5,250,181, which teaches the use of an aqueous solution containing a caustic, an aliphatic mercaptan, and optionally a sulfide to produce an aqueous layer containing metal polysulfides and a clear fluid layer having a reduced elemental sulfur level. Further, U.S. Pat. No. 5,199,978 teaches the use of an inorganic caustic material, an alkyl alcohol, and an organo mercaptan, or sulfide compound, capable of reacting with sulfur to form a fluid-insoluble polysulfide salt reaction product at ambient temperatures.
While such methods have varying degrees of success, there still exists a need in the art for reducing elemental and organic sulfur pick-up by hydrocarbon products when transported in pipelines. Reducing the elemental and organic sulfur pick-up by hydrocarbon products can either eliminate the processing requirements after the pipeline or reduce the operating cost of these processes.